Short wave antenna system



Dec. 6, 1938.

w. BEIRNDT ET AL Filed Aug. 1, 1935 134 i Fig.2 2

may mm'uiA/cv APPA RA 70s H/6/1 FREQUENCY APPABA r05 mmvroas WALTER BERNDT ALBRECHT GOTH E ATTORNEY.

Patented Dec. 6, 1938 UNITED STATES PATENT OFFICE snoa'r WAVE ANTENNA SYSTEM Application August 1,

1935, Serial No. 34,196

In Germany August 31, 1934 3 Claims.

The dipoles as frequently used in the short wave fleld have the disadvantage of absent radiation in the axes thereof, a condition which is detrimental for many purposes. Neither with a vertical dipole alone nor with a horizontal dipole alone is it possible to obtain horizontal as well as vertical radiation in an antenna arrangement disposed above a reflector surface. The vertical dipole has a maximum radiation in the horizontal direction, but does not radiate upwards. The horizontal dipole, due to the reflected image in opposite phase, cannot radiate in the horizontal plane. The radiation upwards depends upon its distance above the reflector surface. Through a combination of horizontal and vertical dipoles it is possible to simultaneously obtain radiation both in horizontal and vertical direction, and in accordance with the invention, this is accomplished in the following manner:

The antenna A comprising one or several bent or buckled conductors, is so arranged in front of a reflector surface R that the cute-r ends thereof reach up to the vicinity of the reflector wall. Figures 1 to 6 illustrate different embodiments of the invention. The feeding of the antenna is carried out in such manner that the currents in all conductor parts have the same direction. In adding to the picture of the antenna its symmetrical image (as shown in Figs. 1 to 3), there will be obtained a current whose course has a uniform sense of rotation. The configuration of such an antenna, when located at a sLL ta-ble distance from the reflector surface and uniformly fed by current, produces a diagram approximating that of a frame antenna. By varying the feed or suitable connection with the reflector wall the magnitude of the currents in the vertical conductor parts can be increased over those in the horizontal parts and vice versa. In this way the radiation in the vertical or horizontal direction can be increased without the appearance of zero places in the diagram.

The antenna can be fed symmetrically in the center thereof as in Fig. 4, or through the two outer ends as in Fig. 5, or else at the one end across a symmetrical feed line as in Fig. 6.

Puting it another way, we can say that Figs. 1, 5 and 6 illustrate embodiments of the general principle presented in Figs. 1, 2 and 3. The antenna of Fig. 4. should be understod as representing a common dipole fed from the center, the ends of which are bent against the reflector plane. By bending the dipole ends, the radiation characteristic of this antenna is so distorted that the radiation is substantially uniform in. all directions above ground or the reflecting surface that lie in the plane of the bent dipole. Instead of feeding the dipoles from the center, according to Fig. 4 of the present application, it is also posible to provide the feeder connections at two ends, according to Fig. 5, or to employ only one dipole bent in a half circle and fed from one end, according to Fig. 6. In all these cases, the radiation diagrams of the antennae remain the same. The antenna of the invention thus has a radiation diagram corresponding to the diagram of a loop antenna, although its function is vastly different. The dimensions of a loop antenna are always small compared to the wavelength, while the antenna of the present invention has dimensions comparable to the wavelength. The present antenna is, therefore, especially suitable for short waves where a loop antenna of the prior art canont collect sufiicient energy from the radiation field due to the necessary, very small dimen- 810115.

In combining several antennae of the aforementioned shape disposed above a reflector surface, practically any desired directional effects can be obtained.

It is advisable to provide an adaptation, i. e., obtain a, matching of impedances, between antenna and feed line that is as favorable as possible.

What is claimed is:

1. A short wave antenna system comprising a dipole bent substantially into a semi-circle, and a plane reflecting surface at right angles to the plane of the dipole and close to the ends thereof.

2. A short wave antenna system comprising a dipole bent substantially into a semi-circle, and a plane reflecting surface at right angles to the plane of the dipole and close to the ends thereof, said dipole having symmetrical connections extending therefrom to translating apparatus.

3. A short wave antenna system comprising a dipole bent substantially into a semi-circle, and a plane reflecting surface at right angles tothe plane of the dipole and close to the ends thereof, and means for energizing said dipole, whereby radiation is substantially uniform in all directions that lie in the plane of the dipole on that side of the reflecting surface on which said dipole is located.

WALTER BERN'DT. ALBRECHT GOTI-IE. 

